Compressor wheel



IAug.r 20, 195.7 A. w. GARDINER COMPRESSOR WHEEL Filed May 2o. 1952 a II 32 I Inventor l @Kga/2T@ azef 2,803,397 Patentedl Aug. 20, 1.957

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COMPRESSDR WHEEL Arthur W'.' Gardiner, Indianapolis, Ind., assignor toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareApplication-May 20, 1952, Serial No; 288,889

4 Claims. (Cl. 230-134) This invention relates to disk-like wheelshaving thickened rim or hub portions and more particularly to themanufacture of compressor wheels or disks for multistage axial owcompressors.

Axial flowcompressorsfor'raircraft gars turbines, and others thatinvolve high-compressionratios, necessarily include'a largenumber-ofstages.Y Such compressor rotors are usually built up-vof a'series-ofcoaxial wheels that haveiintegral thick rim portions that Vcarryspacedblade rows` and spaced-thin'disk'portions that Aserve to tensionthe rim portions against the centrifugal stresses imposed by rotation.The wheels are provided with intermediate spacer rings that may beintegral with the rim portions, and are assembled into a drum-likerotor. The rotor has heavy wheels at its ends which include projectingshaft portions for j ournalling. A central tie rod extends through therotor and interconnects the end wheels to retain the rotor in assembledrelation. The wheel disks are centrally apertured about the tie rod, andthe disks may be thicker around the aperture to form a hub-like portion.The hub-like portion may be mounted on the tie rod, or on a centraldriving shaft, for rotation therewith; but it is usually preferable totransmit the driving torque to the wheels through their rim portions,rather than through their disk portions, and to provide some clearancebetween the hub-like portions and the tie rod.

The wheels for compressor rotors are presently made with integral rimand disk portions by forging and machining aluminum or stainless steelstock, and while they perform satisfactorily, they are expensive anddifficult to manufacture for they require large presses for the forgingoperation and extensive machining. The reason for the excessive cost anddifficulty that is encountered in the manufacture of integral wheels isthat a large amount of metal must be moved by forging and removed bymachining. The wheels should have a high strength to weight ratio towithstand centrifugal stresses; therefore, casting of the wheels toreduce the manufacturing problems is undesirable.

An object of my invention is to devise a wheel for a multi-stage axialdow air compressor that may be readily manufactured at low unit cost andthat will have a high strength to weight ratio.

Another object of invention is to fabricate a wheel for a multi-stageaxial ow air compressor from several parts, formed and united in such amanner as will result in a wheel having high strength.

In carrying out these objects, it is a further object to form an axialflow air compressor wheel having a thick lade carrying rim portion, anda thin tension disk portion, by brazing serrated rings to the sides ofcomplementarily serrated disks.

Further objects and advantages of my iA Je-ation will be apparent fromthe following description, reference being had to the accompanyingdrawings, wherein a preferred form of my invention is clearly shown.

ln the drawings: Figure l is a partial view taken in sectie-n along theaxis of a multi-stage axial ow air com- 2 pressor rotor incorporating myinvention; Figure 2 isganp` enlarged view of a portion of Figure 1;andFigure 3;'isanf. enlarged view taken along the line 3--3rofFigure-land; partially in section.

Referring now to the drawings in detail andrnore particularly to Figure1, the compressor rotor is made-up:r of a series o-f interlocked coaxialwheels 10 -that are clamped in assembled relation by a tie rod v12thatextends between the heavy end wheels at either end of the rotor,A onlythe outlet end wheel 14 being illustrated.' The end; wheels are formedwith protruding shaft portions Y(notti shown) so that the compressorrotor mayV be suitably: journalled for rotation. Each wheel is equippedwith a;- row` of blades 16,'that are dovetailed into the Y, rim; and;secured therein against axial movement bythe radial pins t8; Therims ofthe wheels may have a p rogressivein-A creasein diameter as the bladesbecome progressively; shortertowardthe outlet end so `as to providearotor-ofi constant overall diameter. The rims of the wheels are?interlockedto each other by therlongitudinal pins 20 3sothatdrivingtorque may be transmitted throughthe rim,- portionsof therotor, and the wheels are centrally aper tured about the tie rod 12.

Thewheelszrare composite structures havinggthick bladecarrying ,rimportions `and thin tensionk ,diskfportionst and are constructed inaccordance with my invention by brazing the spirally threaded rings 22and 24 to the opposite sides of the complementarily threaded thin disks26 in such a manner that the crests of the threads on the rings matewith the roots of the threads on the disks. The disks 26 are primarilytension members and are preferably made from cross-rolled sheet steelsuch as is generally used in the manufacture of circular saws and plowdisks; the cross-rolling imparting equal physical properties in alldirections and resulting in a disk that will perform as well as if ithad been forged. The disks 26 may be slightly tapered toward the margin,however, tapering is not vital. Without tapering, the machining of thedisk surfaces may be restricted to cutting the radially directed spiralthreads. The rings 22. and 24 are preferably steel and are provided withcomplementary spiral threads, and the rings are unitarily united to thedisks 26 by brazing the threaded surfaces together. As best seen inFigure 2, the threaded surfaces may be cut substantially coextensivewith the planes of the unthreaded surfaces of the disks 26 after theyhave been cross-rolled to a desired thickness so as to reduce oreliminate further surface cutting on the disks. The threadedinterconnection between the rings and disk provides a multitude ofinter-engaging surfaces between the rings and disk that prevent theirseparation from centrifugal forces, and that furnish a large bondingaree. in a relatively small space for brazing.

A concentric series of radially spaced serrations or corrugations may beprovided in the mating surfaces of the rings 22 and 24 and the disk 26for brazing them into a unitary wheel in lieu of the threaded or spiralserration previously described. Wheels so constructed will performsatisfactorily, but I prefer to utilize a threaded interconnectionbecause of its inherently precise registerability, and because itsmanufacture is much more economical and simple.

The wheels 1d may also be provided with a thickened hub portion bybrazing the spirally threaded rings 28 and 3@ to the opposite sides ofthe complementarily threaded inner portions of the disks 26. Figure 3illustrates how my spirally threaded interconnection appears when viewedfrom an axial direction.

In the preferred form of my invention the rings 24 are formed with anintegral annular flange portion 32 that acts as a spacer between thewheels 10; however, separate spacer rings may be used between the wheels10 if desired.

The preferred embodiment of the invention has been describedfully inorder to explain the principles of the invention. It is to be understoodthat modifications of structure may be made by the exercise of skill inthe art within the scope of the invention which isV not to beV regardedas limited by the detailed description of the preferred embodiment.

I claim:

1. A composite blade supporting Wheel structure comprising a disk havingan outer peripheral surface and oppositely disposed substantiallyvertical side surfaces, one of said side surfaces having a spirallythreaded portion, a ring forming a part of said composite wheelstructure, said ring having a spirally threaded complementary surface tosaid one side and having the crests of its threaded surface mating withthe roots of the threaded portion of said one of said side surfaces,said crests and said roots Vwhen in engaging relation fixing said ringto said disk against relative radial and rotary movement with respect toeach other, and means fixing said disk and said ring against axialmovement whereby said ring and disk forms a thickened blade supportingrim portion. t

2. A composite blade supporting Wheel structure as dened by claim 1wherein said means fixing said disk and said ring against axial movementcomprises a brazed bond between said ring and said disk.

' 3.'A composite blade supporting Wheel structure as defined by claim 1wherein an annular row of blades are secured to said thickened bladesupporting ring portion and said ring includes an integral annularspacer flange projecting axially of said blades.

4. A composite blade supporting wheel structure comprising a disk havingan outer peripheral surface and oppositely disposed substantiallyvertical side surfaces, each of said side surfaces having a spirallythreaded portion, a ring associated with each of said side surfacesforming a part of said composite Wheel, each ring having a spirallythreaded complementary surface to its associated side surface and havingthe crests of its threaded surface mating With the roots of the threadedportion on the associated side surface, said crests and said roots whenin engaging relation xing said rings to said disk against relativeradial and rotary movement with respect to each other, and means fixingsaid disk and said rings against axial movement whereby said rings anddisk form a thickened blade supporting rim portion.

References Cited in the le of this patent UNITED STATES PATENTS 906,400Ferranti Dec. 8, 1908 927,515 Ehrhart July 13, 1909 1,210,978 Parsons etal. Ian. 2, 1917 1,637,750 Kilham Aug. 2, 1927 1,895,133 Quarnstrom Jan.24, 1933 2,137,044 Dawson NOV. 15, 1938

